Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers. Free and in-browser.
Edit either field — the other updates live. Valid range is 1–3999. Examples: 2024 ↔ MMXXIV.
How to use the Roman Numeral Converter
- 1Choose your direction: use the number field to convert a decimal into Roman numerals, or the numeral field to convert Roman numerals back into a number.
- 2Type or paste your value, for example enter 2026 in the number box or MCMXLIV in the numeral box.
- 3The converted result appears instantly as you type, with no button press or page reload needed since it runs in your browser.
- 4Check the validation message if a Roman numeral is malformed (like IIII or IC) and correct it to a valid sequence.
- 5Click the copy button to copy the result to your clipboard for pasting into credits, documents, or designs.
- 6Clear the field and enter another value to convert as many numbers as you like, all offline.
About the Roman Numeral Converter
The Roman Numeral Converter turns ordinary numbers into Roman numerals and translates Roman numerals back into their decimal values, both directions in a single tool. Type a number like 2026 and it returns MMXXVI; paste MCMXLIV and it returns 1944. Everything happens locally in your browser using JavaScript. Nothing you enter is uploaded, logged, or sent to a server, so you can convert dates, page references, or private figures without any data leaving your device, even offline once the page has loaded.
Under the hood the number-to-numeral direction uses the standard subtractive system: the converter walks through value-symbol pairs from largest to smallest (M=1000, CM=900, D=500, CD=400, C=100, XC=90, L=50, XL=40, X=10, IX=9, V=5, IV=4, I=1), subtracting each value as many times as it fits and appending the matching letters. This is why 4 becomes IV rather than IIII and 90 becomes XC. The reverse direction reads left to right and subtracts when a smaller symbol sits before a larger one, so it correctly parses IX as 9 and validates that the input follows real Roman rules instead of accepting nonsense like IC.
Concrete uses show up constantly. Filmmakers and publishers need copyright years in end credits and title pages (MMXXV). Students studying history, Latin, or clock faces check their answers instantly. Writers number book chapters, appendices, and outlines with numerals. People designing tattoos, wedding invitations, watches, and building cornerstones want an accurate rendering of a meaningful date. Quiz makers and teachers generate practice problems both ways.
A practical tip: classical Roman numerals top out at 3999 (MMMCMXCIX) because there is no standard single-character symbol for 5000 or higher without overlines, so keep values in the 1 to 3999 range for portable, universally readable output. For dates, convert each part separately if you want day, month, and year shown distinctly. The instant two-way conversion makes it easy to learn the pattern by experimenting rather than memorizing a chart.
Frequently asked questions
Why does the tool stop at 3999?
Standard Roman numerals only have symbols up to M (1000). Representing 4000 and above requires repeating M many times or using overlined letters (a bar meaning times 1000), which are not part of the basic character set and render inconsistently across fonts. To keep output clean and universally readable, the converter limits values to 1 through 3999.
Why does it show IV instead of IIII for four?
The converter uses the subtractive notation that is the modern standard: when a smaller symbol precedes a larger one it is subtracted, so 4 is IV and 9 is IX. The older additive form IIII appears on some clock faces but is not standard, so this tool produces the conventional subtractive version.
Is zero or a negative number supported?
No. The Roman system has no symbol for zero and no concept of negative values, so those inputs cannot be represented. The tool only converts positive whole numbers, and it ignores decimals since fractions were written with a separate system the Romans used for twelfths.
Does the numeral input accept lowercase letters?
Yes. You can type mcmxliv or MCMXLIV and get the same result, since the parser is case-insensitive. It does, however, check that the sequence follows valid Roman ordering, so an impossible combination like IC or VX will be flagged rather than silently converted.
Can I use this without an internet connection?
Yes. Because all conversion logic runs in JavaScript inside your browser, once the page has loaded you can keep converting numbers with the connection off. Nothing is sent to a server, which also means your inputs stay entirely private on your own device.
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Frequently asked questions
What range is supported?+
Standard Roman numerals from 1 to 3999.